1. Field of the Invention
The present invention pertains to a method and apparatus for molding lenses, and particularly to a method and apparatus for molding lenses such as contact lenses which have a finished edge and which are suitable for wearing directly on the eye. The invention more particularly pertains to a novel method and apparatus for molding contact lenses and making their containers which utilizes continuous web feeding methods wherein the lenses are molded between posterior and anterior mold cavities formed in first and second webs of material, respectively. The webs are brought together in aligned fashion by synchronized feeding mechanisms for curing of a liquid lens material previously disposed within one of the cavities, and thereafter separated from one another to expose the molded lenses. In an advantageous embodiment of the invention, packaging containers for the molded lenses are formed in the same web of material in which the lenses are molded.
2. Description of the Related Art
Cast molding of contact lenses has proven a reliable and economical method of high volume lens production. In this regard, manufacturing methods of molded lenses have seen increased emphasis on mold techniques which consistently produce non-reject lenses on a large production scale. Attention is directed to U.S. Pat. No. 5,271,875 which issued on Dec. 21, 1993 and is of common ownership with the present application, the '875 patent being incorporated herein by reference. The '875 patent relates to a method of molding a contact lens using anterior and posterior mold halves which are used only once by being brought together to mold the lens therebetween, separated following curing of the lens material, and then discarded. As described in the '875 patent, the mold halves include tapered side walls to form cooperating alignment means between the mold halves as they are brought together and clamped (see FIGS. 2-17 therein) or taper-locked (see FIGS. 21-24 therein) to provide the needed force to squeeze the mold halves together during polymerization. More particularly, deformable rim and annulus features 52 and 47 encircling the surface cavities of the anterior and posterior mold halves, respectively, are provided for engaging and deforming against one another during curing of the monomer contained in the mold by virtue of a clamping force applied to the mold halves. The juncture of the rim and annulus features forms the finished edge of the lens in addition to accommodating shrinkage of the lens material during curing thereof by slowly bringing the respective mold surface cavities toward one another as the rim and annulus features forcibly deform against one another.
While the method and apparatus of the '875 patent is effective at consistently producing substantial numbers of non-reject lenses on a large manufacturing basis, there remains a desire to continuously reduce costs through, for example, improved automation and packaging techniques.